Christian Müller, a researcher at the German Research Center for Artificial Intelligence (DFKI) in Saarbrücken, who co-developed the new system, says the idea is to enable drivers to adjust everything from the volume of the car stereo to the climate-control settings while keeping their hands on the wheel and eyes on the road.

The prototype interface uses several sensors to detect the movement of a driver's right index finger as it disrupts an electric field. It is based on the same principle as the theremin, a musical instrument that is played without being touched. Electromagnetic sensors located in the dashboard detect finger movements, providing the driver is holding the wheel in the recommended ten-to-two position and is driving straight. By detecting the different shapes the driver's finger draws in the air, the system can detect and interpret a wide range of commands, says Müller.

Creative sf author Douglas Adams was ahead of the curve in describing a gesture-controlled radio in his 1979 novel The Hitchhiker's Guide to the Galaxy:

A loud clatter of gunk music flooded through the Heart of Gold cabin as Zaphod searched the sub-etha radio wave bands for news of himself. The machine was rather difficult to operate... as the technology became more sophisticated... all you had to do was wave your hand in the general direction of the components and hope.
(Read more about Douglas Adams' Gesture-Controlled Radio)